There is a vital need for quantitative assessment of tumor burden and cancer therapy response by in vivo imaging. Computed tomography (CT) and standard magnetic resonance imaging (MRI) cannot provide information on the molecular, biochemical and physiologic properties of cancer tissues, and may also fail to specifically distinguish viable tumor from benign conditions or necrotic tumor. Therefore, novel quantitative imaging techniques and protocols are needed to reveal biomarkers of molecular events induced by cancer therapy. In particular, early imaging of molecularly targeted pathways predicted to be essential for effective cancer therapy is highly likely to play a key role in patient management in the future. Development and use of quantitative imaging for early therapy assessment will greatly facilitate patient management, by sparing patients from weeks or months of toxicity and ineffective treatment. Additionally with the increasing rate of therapy development and related therapy trials, the development of minimally invasive, yet specific and accurate measurements of early therapeutic response has become of critical importance. Because none of the currently available imaging technologies can provide all of the needed information, there is an important trend to combine information from two or more imaging techniques. This need for multimodality imaging has led to a UPCI decision to combine two existing CCSG-funded shared facilities (MRI and PET), and to add a third modality (optical small animal imaging) to create a new, integrated UPCI shared facility, the In Vivo Imaging Facility (IVIF). In addition, the IVIF also incorporates the NCI-funded (CCSG supplement) Imaging Response Assessment Team (IRAT) program, which integrates the clinical research components of the IVIF. The IVIF provides expertise, to most of the CCSG programs of UPCI, in preclinical, translational, and clinical imaging using x-ray, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and optical imaging modalities. The goals of the facility are 1) to provide preclinical assessment of biomarker expression throughout cancer treatment, 2) to provide methods for monitoring biological therapy, 3) to facilitate protocol development for cancer detection, diagnosis, and staging and 4) to advance methods for evaluating early therapy response prognosis following treatment. The IVIF has already made significant contributions to UPCI research by providing non-invasive imaging biomarkers for tumor diagnosis, staging, and prognosis in addition to implementation of protocols for early therapy response assessment. The IVIF has a broad scope and is integral to the Cancer Epidemiology and Prevention Program (e.g. for screening for lung lesions in heavy smokers). The services provided incorporate a multi-modality approach and include measurements of a number of biomarkers for the early evaluation of new therapies, including: 1) tumor volume measurement and Response Evaluation Criteria in Solid Tumors (RECIST) assessment or tumor growth analysis (MRI, PET, & Optical); response to cancer therapy analysis 2) tumor glucose metabolism, cell proliferation, and apoptosis (F-18 FDG PET, F-18 FMISO and F-18 ML-10); 3) tumor cell proliferation (F-18 FLT PET); 4) tumor capillary transfer rates (MRI); 5) spectroscopic analyses for total choline (MRI), citrate, and intracellular sodium (MRI); 6) synthesis of targeted contrast agents (MRI, PET, and Optical); 7) cell labeling and tracking (MRI & Optical); and 8) custom methods development (MRI, PET, & Optical).